I don't understand why Apple does not use SSD drives in the Macbook Air like some other manufacturers to (e.g. Asus, Samsung). The technical specifications of the Macbook Air on Apple's website never mention the use of SSDs.

Apple only speaks of flash memory in the Macbook Air.

How does the use flash memory compare to SSDs? What are the benefits?

Edit:

Does dropping the SATA interface improve the theoretical throughput and latency of I/O operations to the hard-disk?

9 Answers
9

What is the benefit of using flash memory in the Macbook Air?
How does the use flash memory compare to SSDs? What are the benefits?

The Macbook Air uses an SSD. Apple markets it as merely flash memory because in the consumer market there are only two storage types - flash and hard drives. The typical consumer Apple is aiming for does not know what SSD is, nor do they care. But they do know what a "flash drive" is, and due to aggressive marketing they believe it's better than the alternative.

It's a custom form-factor SSD, but it uses a SATA flash controller, and the Air reads it just as if it were any other SATA drive. OS X does, however, understand it as an SSD and treats it slightly differently from a hard drive in order to use it to its full potential, but in every other respect it's just a custom form factor SSD.

The reason Apple uses a custom form factor SSD is for size, weight, and - most important to Apple - cost.

They have both Toshiba and Samsung on the line for supplying these SSDs. When they get a poor price from one, they go to the other. They need this because the SSD is one of the few things in the Air that requires custom PCB layout and comes from multiple suppliers. The pinouts and circuitry are different between the samsung and toshiba flash controllers, so they can't build them into the main PCB as Apple would prefer, without locking them into one vendor or the other.

The flash market is so volatile right now that they can't lock themselves into just one supplier, especially since some 80% of Apple's revenue comes from products that use copious amounts of flash. If they thought they could get a better price manufacturing their own flash, they'd have their own plant - or ten. Instead it's cheaper to play the major flash producers against each other to get the lowest cost.

So:

The Storage in the Air is a SATA interfaced SSD

It's not on the main PCB to give them the ability to use different parts from different suppliers

It's not a 2.5", 1.8", or SATA slim interface because they needed it to be smaller - they designed their own interface, but it's still SATA, just with a different low insertion force connector

They aren't using the latest and greatest chipsets due to cost and power consumption

They aren't using hard drives due to size, weight, and power consumption

Is this answer still valid for the retina Macbook Pro? See this tweet for example. It points out how I/O interfaces are dropped in Apple's implementation. But I believe that Apple still uses the SATA interface.
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gentmattJun 13 '12 at 17:15

1

@gentmatt The Retina Macbook Pro uses an SSD module with a controller/interface. It is not the same form-factor as the SSD used in previous macbook airs, but there is a SATA drive controller (the Samsung S4LJ204X01 was present in the ifixit teardown retina macbook pro). See the iFixit teardown, step 10, for the SATA drive details. So most of the points of this answer are still correct. You'll find that the new 2012 air has a different connector, but it doesn't match that one either.
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Adam DavisJun 14 '12 at 20:07

Ok, thanks. I took a look at the teardown yesterday.
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gentmattJun 14 '12 at 20:09

They are pretty much the same. The only thing that differentiate SSD with a flash is the fact is housed in a big case. And the MacBook Air flash memory is attached to specific card inside the MacBook Air.
To save space for starters (there is simply not any space left for a real SSD) and I thought is served better cooling too.

@gentmatt Let me be pedantic and point out: The RAM in the MacBook Air (e.g. the 2GB RAM, 4GB RAM) is soldered to the mainboard, and can't be upgraded (by a layperson). What each of you is referring to is the flash storage, which is on a separate card (module), which can be upgraded. Calling the flash storage simply "memory" is an invitation for ambiguity. :-)
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Chris W. ReaMar 20 '12 at 13:49

@Richard No, SSD means Solid State Drive. Today 2.5" and 3.5" cased flash based SSDs are legion but are not the only type of storage to be called SSD. I remember SSDs being big extension cards (sometimes using multiple slots). Even today you can find this kind of SSDs. There are also RAM based SSDs. With the amount of RAM you can fit in a modern workstation, mounting a RAM disk instead of the expensive RAM based SSDs is a reasonable alternative. Also don't forget the future of SSDs coming in the form of nRAM, ReRAM or maybe PMC memory chips.
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CoyoteApr 3 '12 at 0:14

The Macbook Air comes with an SSD which uses an custom mini-PCIe/mSATA connector also found in some Dell and ASUS computers.

Some notebooks (notably the Asus Eee PC, the MacBook Air, and the Dell mini9 and mini10) use a variant of the PCI Express Mini Card as an SSD.

The connector on the motherboard looks like this (the one on the left):

The SSD looks like this:

The Macbook Air does not drop the SATA interface. It uses a variant of the mini-PCIe/mSATA connector. You can buy upgrades which work at up to 6GBPS here for example.

Apple uses the term Flash Storage as it's exactly what this Solid State Drive is as opposed to the mechanical counterparts Hard Drive Disks. An SSD is (mainly) composed of a main board, a connector, a controller and flash memory chips. At least modern SSDs use flash memory as opposed to RAM based SSDs (with backup batteries for storage or without for temporary operations).

The great advantage of the smaller SSD with mSATA connectors comes from their form factor. They are slimmer, thiner and take less room on the motherboard. Smaller connectors require less space and less circuitry to connect with other components.

If you want to connect the SSD in a laptop or desktop PC there are some pretty siple adaptors like this one:

It seems out of scope but for a good overview of the advantages of SSDs and HDDs see here.

Note: I previously thought the connector was a stock mSATA connector which is a PCI Express Mini Card-like connector which is electrically SATA. But apparently it is a variant. See this question for more info about the connector.

My wife owns one of these and they are great at retrieving large amounts of data and launching programs with large libraries (iPhoto, iMovie, iTunes...).

The genius of the unibody construction is that Apple can cut out all of the protective cases that normally are built around commodity parts to achieve much denser, lighter and slimmer products without sacrificing durability of the product.

By eliminating (or severely honing to a minimum) the protective cases around the battery and the mass storage drive (whether you call it a SSD or flash based storage - the chipsets in the MacBook Air and inside all SSD as well as in PCI card based storage are more the same than they are different.

The air is simply the first machine that required this sort of design, but I expect that soon all macs where size and weight are important can shift to a raw circuit board with a connector type storage rather than conforming to the legacy 3.5 inch and 2.5 inch packaging boundaries established long ago by drives with spinning magnetic platters.

Apple has honed the craft and practice of encasing components in a durable outer shell from the iPhone, to the iPod to the iPad as well as the MacBook Air. I would expect the MacBook Pro, mac mini and eventually the iMac to adopt these space saving designs over time. As volumes of mac sales grow - more custom design can be justified to save shipping costs, material costs, recycling burden and just make things as small as practical.

SSD is just marketing speak. Solid State Drive. It implies that it's a seperate component unit with all the stuff you usually associate with a drive - power connectors, SATA data connectors, a physical form factor which provides an indication of where is can be used (2.5" SSD, 1.8" SSD etc).

The storage in the Air is not a "drive", it's just storage. It doesn't share any of the physical aspects of an SSD other than the important one that it uses Flash Memory.

To simplify the answer, the storage in an Air is just raw Flash stuck straight to the motherboard. Throw that flash into an enclosure meeting standard dimenions and with standard connectors and you have an SSD. Why don't they use SSD? Simply space, all that periphery is just wasted space.

The storage in the Air is a "drive" to the system and it can be formatted, partitioned, etc. The physical flash storage on a board doesn't physically look like a HD and so, the confusion. so, there's a physical SSD that mimics a hard disk in shape and form and there's a virtual SSD that mimics a hard disk in functionality.
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RichardMar 20 '12 at 14:54

As already mentioned, size was the reason, you can't put a case inside a MBA, no room for it. However, despite the fact that most SSDs use NAND-based flash memory, there's another thing in the SSD Drives that the MBA doesn't have "next to it", and that is the controller. The MBA obviously has a controller for the drive, but possibly not in the same position/size than a regular SSD.

1. Flash memory is the technology, not the product.

Everyone has seemed to focus on the size aspect, but "flash memory" is really just the technology, and not really an end product. It is used in both USB storage and SSDs (the difference being the quality of the NAND memory) and it was just unfortunate that the name got tagged along and automatically associated with a particular product (USB then, SSD now) — just like how any mention of "Wiki" reminds one of Wikipedia, although it really only refers to the technology underneath.

For example, this article from Seagate, a leading manufacturer of SSDs and HDDs, does not differentiate the two terms as different products. If you also look at Apple's tech specs, they use the term flash storage, and not flash memory, which is just their way of calling it.

2. Marketing — "flash" conveys notions of lightning speed

I believe this is the primary reason — the word "drive" conjures up images of something in motion. From a marketing point of view, that is the exact opposite of the image you wish to convey when you tout these things as not having any movable parts. Now compare that with "flash", which conveys notions of transience, speed (think Flash Gordon), etc. Given Apple's meticulous care for detail, I wouldn't be surprised if they consciously decided to ditch the word "SSD" because of this.